This application discloses and claims an overload status indicator for a compressor that signals an overload condition following the shut down of the compressor.
Scroll compressors are becoming widely utilized in refrigerant compression applications. In a scroll compressor a pair of scroll members each have a base and a generally spiral wrap extending from the base. The wraps interfit to define compression chambers. One of the two scroll members is caused to orbit relative to the other. As the wraps orbit relative to each other, the size of the compression chambers decreases and an entrapped refrigerant is compressed.
There are many challenges with scroll compressor design. One of the challenges relates to the mass flow through the compressor. The compressors are typically incorporated into a refrigerant cycle, and there is the possibility of loss of charge in the refrigerant from several spots in the cycle. During a loss of charge situation, the mass of refrigerant flowing through the compressor decreases. Continued operation at loss of charge situations can have undesirable side effects. Thus, there is an effort to identify loss of charge situations.
One protection element incorporated into compressors is a motor protector. A motor protector senses several variables within the compressor housing and stops operation of the electric motor driving the compressor should conditions indicate some problem with the compressor or its associated refrigerant cycle. Typically, the protector is actuated by an anomaly in the power supply to the electric motor (i.e., a spike in voltage or current) or, due to excessive heat. Motor protectors have been typically incorporated into the windings of the motor stator.
Individuals servicing these compressors frequently mistake a compressor in which a motor protector has been activated to be a malfunctioning compressor. Consequently, these compressors may be wrongly sent in for repair rather than allowing the overload condition to pass or the compressor to reset. Indeed, in some cases, the compressor may be replaced by another unit, resulting in further unnecessary cost and expense. Moreover, the activation of the motor protector may indicate a system wide problem such as loss of refrigerant charge or failed condenser fan motor. Accordingly, a technician may forego troubleshooting the refrigerant system, mistakenly believing a faulty compressor motor to be the problem.
Currently, to determine whether the compressor is in a temporary overload condition, a technician must measure the resistance between the motor common winding and run/start of the winding because of the motor protector's incorporation into the motor's windings. This analysis permits the technician to determine if the circuit has been broken as a consequence of activation of the motor protector. Due to the difficulty of performing this task, the technician may not take the time to conduct this analysis.
A need therefore exists for a simple and inexpensive device to signal that the compressor is in an overload condition.